Node.js fs.filehandle.truncate() Method Last Updated : 29 Dec, 2022 Comments Improve Suggest changes Like Article Like Report The fs.filehandle.truncate() method is an inbuilt application programming interface of class fs.filehandle within File System module which is used to truncate the particular file object and only that much byte will be retained which passed as an integer in truncate() method. Syntax: const filehandle.truncate(len) Parameter: This method takes the length of bytes till which this file has to be truncated.Return value: This method returns an pending promise which contains no value in it. Below programs illustrates the use of fs.filehandle.truncate() method in Node.js: Example 1: Filename: index.js JavaScript // Node.js program to demonstrate the // filehandle.truncate() method const fs = require('fs'); const fsPromises = fs.promises; // Initiating asynchronise function async function funct() { // Initializing following variables let filehandle = null; let prom = null; try { // Data before operation console.log("data before operation: " + fs.readFileSync('example.txt', 'utf8')); // Creating and initiating filehandle filehandle = await fsPromises.open('example.txt', 'r+'); // Truncating the file // by using truncate() method prom = filehandle.truncate(5); } finally { if (filehandle) { // Data after operation console.log("data after operation: " + fs.readFileSync('example.txt', 'utf8')); // Close the file if it is opened. await filehandle.close(); } } } funct().catch(console.error); Run index.js file using the following command: node index.js Output: data before operation: ABCDEFGHIJK data after operation: ABCDE Example 2: Filename: index.js JavaScript // Node.js program to demonstrate the // filehandle.truncate() method const fs = require('fs'); const fsPromises = fs.promises; // Data for the new file let data = "This is a file containing " + "a collection of books."; // Name of the file to be created let file = "books.txt"; // Creating the new file 'books.txt' fs.writeFile(file, data, (err) => { // Catching error if (err) { console.log(err); } }); // Using fs.exists() method fs.exists(file, (exists) => { if (exists) { console.log( "content of file before operation: " + (fs.readFileSync(file))); } }); // Initiating asynchronise function async function funct() { // Initializing filehandle let filehandle = null; try { // Creating and initiating filehandle filehandle = await fsPromises.open(file, 'r+'); // Truncating the file // by using truncate() method prom = filehandle.truncate(4); } finally { if (filehandle) { // Close the file if it is opened. console.log( "content of file after operation: " + (fs.readFileSync(file))); await filehandle.close(); } } } funct().catch(console.error); Directory structure before running the program: Directory structure after running the program: Run index.js file using the following command: node index.js Output: content of file before operation: This is a file containing a collection of books. content of file after operation: This NOTE: The above program will not run on online JavaScript and script editor.Reference: https://nodejs.org/dist/latest-v12.x/docs/api/fs.html#fs_filehandle_truncate_len Comment More infoAdvertise with us R rohitprasad3 Follow Improve Article Tags : Web Technologies Node.js Node.js-fs-module Similar Reads Node JS fs.readFile() Method ​In Node.js, the fs.readFile() method is a fundamental tool for reading files asynchronously, allowing your application to remain responsive while accessing file data. 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